A variety of contact switches are known. Filion et al, U.S. Pat. No. 5,448,028, discloses an arm rest electrical switch arrangement for soft interior trim panels. The switch has a flexible skin including indented or depression areas shaped and oriented to receive a person's finger tip. A membrane switch is encapsulated in a foam layer adjacent to the depression area and positioned inside a soft interior trim panel and fixed in position during foaming and curing of the foam layer. The application of pressure with a finger in the depression area will close the membrane switch. This is an on/off type switch and can be utilized to raise or lower windows or to move mirrors in an automobile.
Latasiewicz, U.S. Pat. No. 4,551,586, discloses a membrane switch assembly having a plurality of contact bearing layers. Each contact bearing layer contains a plurality of contact members connected to a plurality of leads which extend from the switch assembly. The contact members are placed as desired in registration with each other or with apertures in spacer layers. This arrangement permits contact between desired contact members themselves, between desired contact members in a base/ground layer or between individual contact members in the base layer. A substantial number of possible combinations of contact members enables such a switch assembly to be readily adapted to a number of control patterns as dictated by the switching requirements of the desired device. Nevertheless, this assembly is also limited to on/off type switching.
Bennewitz, U.S. Pat. No. 4,463,234, discloses a tactile feel membrane switch assembly. A plurality of membrane switches in a keyboard array are provided with tactile feel utilizing a metal snap dome and a force actuator positioned above the membrane switch. The tactile feel is provided by a sudden decrease in force during actuation of the switch. A snap dome, a force actuator, a dome enclosure and an overlayer are mounted above the membrane switch. These are all provided with a planar, layered construction which enables the metal dome to be free to deflect through its specified travel. The full travel of the metal dome will provide acceptable tactile feel response. When the dome snaps through, it engages a force actuator which forces the membrane down causing the switch contacts to close. Again, this type of switch is also limited to on/off switching.
Larson et al, U.S. Pat. No. 4,403,272, discloses a membrane switch interconnect tail and printed circuit board connection. The switch includes a substrate and a membrane layer with a plurality of conductive elements formed on each of the layers. The layers are conveniently separated by a spacer. The conductive elements are arranged into a pattern forming switch sites or locations. A particular switch is closed by applying pressure to a membrane at the switch location. A connecting tail is attached to a substrate layer. The tail includes a raised portion including a plurality of individual bumps. The bumps may be formed by embossing them in the tail member. Similarly, this switch is also limited to on/off applications.
The present invention provides alternatives and advantages over the prior art.